Torque fluctuation inhibiting device, torque converter and power transmission device

ABSTRACT

A torque fluctuation inhibiting device includes a mass body, a centrifugal element and a cam mechanism. The mass body is disposed to be rotatable with a rotor and be rotatable relatively to the rotor. The centrifugal element is disposed to receive a centrifugal force to be generated by rotation of the rotor and the mass body. When a relative displacement is produced between the rotor and the mass body in a rotational direction, the cam mechanism converts the centrifugal force that acts on the centrifugal element into a circumferential force directed to reduce the relative displacement. Additionally, when the torque fluctuations inputted to the rotor have a predetermined magnitude or greater, the cam mechanism makes the mass body freely rotate with respect to the rotor.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is the U.S. National Phase of PCT International Application No. PCT/JP2016/071504 filed on Jul. 22, 2016. That application claims priority to Japanese Patent Application No. 2015-162957, filed on Aug. 20, 2015, Japanese Patent Application No. 2015-198244, filed on Oct. 6, 2015, Japanese Patent Application No. 2015-199308, filed on Oct. 7, 2015, and Japanese Patent Application No. 2015-208759, filed on Oct. 23, 2015. The contents of all five applications are herein incorporated by reference in their entirety.

BACKGROUND Technical Field

The present disclosure relates to a torque fluctuation inhibiting device, particularly to a torque fluctuation inhibiting device for inhibiting torque fluctuations in a rotor to which a torque is inputted. Additionally, the present disclosure relates to a torque converter and a power transmission device, each of which includes the torque fluctuation inhibiting device.

Background Art

For example, a clutch device, including a damper device, and a torque converter are provided between an engine and a transmission in an automobile. Additionally, for reduction in fuel consumption, the torque converter is provided with a lock-up device that mechanically transmits a torque at a predetermined rotational speed or greater. The lock-up device is provided with a damper including a plurality of torsion springs.

More detailedly, the lock-up device generally includes a clutch part and the damper including the plural torsion springs. Additionally, the clutch part includes a piston to which a friction member is attached and that is pressed onto a front cover by an action of hydraulic pressure. Then in a lock-up on state, a torque is transmitted from the front cover to the piston through the friction member, and is further transmitted therefrom to an output-side member through the plural torsion springs.

In the lock-up device described above, torque fluctuations (fluctuations in rotational velocity) are inhibited by the damper including the plural torsion springs.

Incidentally, a lock-up device described in Japan Laid-open Patent Application Publication No. 2015-094424 is provided with a dynamic damper device including an inertia member in order to inhibit torque fluctuations. The dynamic damper device described in Japan Laid-open Patent Application Publication No. 2015-094424 is attached to a plate supporting torsion springs, and includes a pair of inertia rings, which is rotatable relatively to the plate, and a plurality of coil springs disposed between the plate and the inertia rings.

BRIEF SUMMARY

A peak of torque fluctuations, occurring in a predetermined rotational speed range, can be reduced in well-known dynamic damper devices including that described in Japan Laid-open Patent Application Publication No. 2015-094424.

However, an axial space is required for disposing the inertia rings and the coil springs, both of which compose the dynamic damper device. In the device of Japan Laid-open Patent Application Publication No. 2015-094424, the dynamic damper device is disposed in a dead space. Hence, the entire device can be made relatively compact. However, in some cases, installation of the dynamic damper device may bring about increase in axial size of the device.

Additionally, well-known dynamic damper devices including that of Japan Laid-open Patent Application Publication No. 2015-094424 can reduce a peak of torque fluctuations in a predetermined rotational speed range. However, when the specification of the engine or so forth is changed, it is required to change the inertia amount of the inertia rings and the spring constant of the coil springs. Hence, coping with such requirement may be difficult in some cases.

It is an object of the present disclosure to make it possible, in a device for inhibiting torque fluctuations in a rotary member, to reduce a peak of torque fluctuations in a relatively wide rotational speed range without increasing the axial space of the entire device.

Solution to Problems

(1) A torque fluctuation inhibiting device according to the present disclosure is a device for inhibiting torque fluctuations in a rotor to which a torque is inputted. The torque fluctuation inhibiting device includes a mass body, a centrifugal element and a cam mechanism. The mass body is disposed to be rotatable with the rotor and be rotatable relatively to the rotor. The centrifugal element is disposed to receive a centrifugal force to be generated by rotation of the rotor and the mass body. When a relative displacement is produced between the rotor and the mass body in a rotational direction, the cam mechanism converts the centrifugal force acting on the centrifugal element into a circumferential force directed to reduce the relative displacement. Additionally, when the torque fluctuations inputted to the rotor has a predetermined magnitude or greater, the cam mechanism makes the mass body freely rotate with respect to the rotor.

When a torque is inputted to the rotor in this device, the rotor and the mass body are rotated by actuation of the cam mechanism. When the torque inputted to the rotor does not fluctuate, relative displacement is not produced between the rotor and the mass body in the rotational direction. Therefore, the rotor and the mass body are rotated in synchronization with each other. On the other hand, when the torque inputted to the rotor fluctuates, the relative displacement is produced between the mass body and the rotor in the rotational direction (the displacement will be hereinafter expressed as “rotational phase difference” on an as-needed basis) depending on the extent of torque fluctuations, because the mass body is disposed to be rotatable relatively to the rotor.

When the rotor and the mass body are herein rotated, the centrifugal element receives a centrifugal force. Then, when the relative displacement is produced between the rotor and the mass body, the cam mechanism is actuated to convert the centrifugal force acting on the centrifugal element into a circumferential force so as to reduce the relative displacement between the rotor and the mass body by the circumferential force. Torque fluctuations are inhibited by the herein described actuation of the cam mechanism. On the other hand, when the torque fluctuations inputted to the rotor has a predetermined magnitude or greater, the mass body is freely rotated with respect to the rotor in the direction that the relative displacement is produced.

Here, the device is composed of the mass body, the centrifugal element and the cam mechanism. Hence, these members can be disposed in radial alignment with respect to the rotor, whereby the axial space of the device can be reduced. Additionally, the centrifugal force acting on the centrifugal element is utilized for inhibiting torque fluctuations. Hence, characteristics of inhibiting torque fluctuations vary in accordance with the rotational speed of the rotor. Moreover, the characteristics of inhibiting torque fluctuations can be also varied by changing the specification of the cam mechanism. Hence, a peak of torque fluctuations can be reduced in as wide a rotational speed range as possible. Furthermore, when the torque fluctuations inputted to the rotor has a predetermined magnitude or greater, the cam mechanism makes the mas body freely rotate in the direction that the relative displacement is produced. Hence, an excessive force can be prevented from acting on the cam mechanism. Consequently, increase in cost of the cam mechanism can be avoided by appropriately set the strength of the cam mechanism, and besides, breakage or damage of the cam mechanism can be avoided.

(2) Preferably, the cam mechanism converts the centrifugal force into the circumferential force directed to reduce the relative displacement when the torque fluctuations are indicated to be less than or equal to a predetermined fluctuation value, and makes the mass body freely rotate with respect to the rotor when the torque fluctuations are indicated to be greater than the predetermined fluctuation value.

(3) Preferably, the cam mechanism makes the rotor and the mass body rotate in synchronization with each other when the torque fluctuations are indicated to be less than the predetermined fluctuation value.

(4) Preferably, the mass body is disposed on an outer or inner periphery of the rotor. In this case, the rotor and the mass body are disposed in radial alignment. Hence, the axial space can be reduced.

(5) Preferably, one of the rotor and the mass body, disposed on an inner peripheral side, includes a recess on an outer peripheral surface thereof. Additionally, the centrifugal element is accommodated in the recess so as to be movable in a radial direction. Similarly to the above, the axial space of the device can be reduced in this case too.

(6) Preferably, a friction coefficient between the centrifugal element and the recess of the one of the rotor and the mass body is less than or equal to 0.1.

(7) Preferably, a friction reducing member is disposed between a lateral surface of the centrifugal element, which is disposed along the moving direction of the centrifugal element, and the recess of the one of the rotor and the mass body so as to reduce friction occurring in movement of the centrifugal element.

(8) Preferably, the cam mechanism includes a cam follower, provided on the centrifugal element, and a cam. The cam, with which the cam follower makes contact, is provided on an inner peripheral surface of the other of the rotor and the mass body that is disposed on an outer peripheral side, and has a shape making the circumferential force vary in accordance with an amount of the relative displacement between the rotor and the mass body in the rotational direction.

Here, the amount of the relative displacement between the rotor and the mass body in the rotational direction fluctuates in accordance with the magnitude of torque fluctuations in the rotor. At this time, the shape of the cam is set such that the circumferential force, into which the centrifugal force is converted, varies in accordance with the amount of the relative displacement. Hence, torque fluctuations can be inhibited as efficiently as possible.

(9) Preferably, the torque fluctuation inhibiting device further includes an urging member that is disposed inside the recess and urges the centrifugal element outward in the radial direction such that the cam follower makes contact with the cam while the rotor and the mass body are not being rotated.

Here, the urging member causes the centrifugal element to constantly make contact with the cam. Therefore, it is possible to eliminate sound to be produced when the centrifugal element is separated from the cam in stop of rotation or when the centrifugal element makes contact (collides) with the cam in start of rotation.

(10) Preferably, the cam follower is a roller disposed on an outer peripheral surface of the centrifugal element.

(11) Preferably, the cam follower is a protruding part that is integrated with the centrifugal element and is provided on the outer peripheral surface of the centrifugal element.

(12) Preferably, the cam mechanism includes a cam follower, provided on the inner peripheral surface of the other of the rotor and the mass body that is disposed on an outer peripheral side, and a cam. The cam, provided on the centrifugal element, makes contact at an outer peripheral surface thereof with the cam follower, and has a shape making the circumferential force vary in accordance with the amount of the relative displacement between the rotor and the mass body in the rotational direction.

(13) Preferably, one of the rotor and the mass body, disposed on an outer peripheral side, includes a recess on an inner peripheral surface thereof. Additionally, the centrifugal element is accommodated in the recess so as to be movable in the radial direction. Preferably, the cam mechanism includes a cam follower, provided on the centrifugal element, and a cam. The cam, with which the cam follower makes contact, is provided on an inner peripheral surface of the other of the rotor and the mass body that is disposed on an inner peripheral side, and has a shape making the circumferential force vary in accordance with the amount of the relative displacement between the rotor and the mass body in the rotational direction.

(14) A torque converter according to the present disclosure is disposed between an engine and a transmission. The torque converter includes an input-side rotor to which a torque is inputted from the engine, an output-side rotor outputting the torque to the transmission, a damper disposed between the input-side rotor and the output-side rotor, and the torque fluctuation inhibiting device configured as any of the above.

(15) Preferably, the torque fluctuation inhibiting device is disposed on the input-side rotor.

(16) Preferably, the torque fluctuation inhibiting device is disposed on the output-side rotor.

(17) Preferably, the damper includes a first damper to which the torque is inputted from the input-side rotor, a second damper outputting the torque to the output-side rotor, and an intermediate member provided between the first damper and the second damper. Additionally, the torque fluctuation inhibiting device is disposed on the intermediate member.

(18) Preferably, the damper includes a plurality of coil springs. Preferably, the torque converter further includes a float member that is rotatable relatively to the input-side rotor and the output-side rotor and supports the plurality of coil springs, and the torque fluctuation inhibiting device is disposed on the float member.

(19) A power transmission device according to the present disclosure includes a flywheel, a clutch device and the torque fluctuation inhibiting device configured as any of the above. The flywheel includes a first inertia body rotated about a rotational axis, a second inertia body, which is rotated about the rotational axis and is rotatable relatively to the first inertia body, and a damper disposed between the first inertia body and the second inertia body. The clutch device is provided on the second inertia body of the flywheel.

(20) Preferably, the torque fluctuation inhibiting device is disposed on the second inertia body.

(21) Preferably, the torque fluctuation inhibiting device is disposed on the first inertia body.

(22) Preferably, the damper includes a first damper to which a torque is inputted from the first inertia body, a second damper outputting the torque to the second inertia body, and an intermediate member provided between the first damper and the second damper. Additionally, the torque fluctuation inhibiting device is disposed on the intermediate member.

According to the present advancement described above, in a device for inhibiting torque fluctuations in a rotary member, a space can be reduced especially in an axial direction, and besides, a peak of torque fluctuations can be reduced in a relatively wide rotational speed range.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a torque converter according to an exemplary embodiment of the present disclosure.

FIG. 2A is a front view of an output-side rotor and a torque fluctuation inhibiting device that are shown in FIG. 1.

FIG. 2B is a diagram according to another exemplary embodiment and corresponds to FIG. 2A.

FIG. 3 is a partial enlarged view of FIG. 2A.

FIG. 4 is a diagram for explaining the actuation of a cam mechanism.

FIG. 5 is a diagram for explaining actuation of the cam mechanism in a condition that excessive torque fluctuations are inputted.

FIG. 6 is a characteristic diagram showing a relation between rotational speed and torque fluctuations.

FIG. 7 is a diagram of a cam mechanism according to modification 1 and corresponds to FIG. 3.

FIG. 8 is a diagram of a cam mechanism according to modification 2 and corresponds to FIG. 3.

FIG. 9 is a diagram of a cam mechanism according to modification 3 and corresponds to FIG. 3.

FIG. 10 is a diagram of a cam mechanism according to modification 4 and corresponds to FIG. 3.

FIG. 11 is a diagram showing another exemplary embodiment of the present disclosure and corresponds to FIG. 3.

FIG. 12 is a diagram showing yet another exemplary embodiment of the present disclosure and corresponds to FIG. 1.

FIG. 13 is a schematic diagram showing application example 1 of the present disclosure.

FIG. 14 is a schematic diagram showing application example 2 of the present disclosure.

FIG. 15 is a schematic diagram showing application example 3 of the present disclosure.

FIG. 16 is a schematic diagram showing application example 4 of the present disclosure.

FIG. 17 is a schematic diagram showing application example 5 of the present disclosure.

FIG. 18 is a schematic diagram showing application example 6 of the present disclosure.

FIG. 19 is a schematic diagram showing application example 7 of the present disclosure.

FIG. 20 is a schematic diagram showing application example 8 of the present disclosure.

FIG. 21 is a schematic diagram showing application example 9 of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic diagram of a condition that a torque fluctuation inhibiting device according to an exemplary embodiment of the present disclosure is attached to a lock-up device for a torque converter. In FIG. 1, line O-O indicates a rotational axis of the torque converter.

[Entire Configuration]

A torque converter 1 includes a front cover 2, a torque converter body 3, a lock-up device 4 and an output hub 5. A torque is inputted to the front cover 2 from an engine. The torque converter body 3 includes an impeller 7 coupled to the front cover 2, a turbine 8 and a stator (not shown in the drawings). The turbine 8 is coupled to the output hub 5, and an input shaft of a transmission (not shown in the drawings) is capable of being spline-coupled to the inner peripheral part of the output hub 5.

[Lock-Up Device 4]

The lock-up device 4 includes a clutch part, a piston to be actuated by hydraulic pressure, and so forth, and is settable to a lock-up on state and a lock-up off state. In the lock-up on state, the torque inputted to the front cover 2 is transmitted to the output hub 5 through the lock-up device 4 without through the torque converter body 3. On the other hand, in the lock-up off state, the torque inputted to the front cover 2 is transmitted to the output hub 5 through the torque converter body 3.

The lock-up device 4 includes an input-side rotor 11, an output-side rotor 12, a damper 13 and a torque fluctuation inhibiting device 14.

The input-side rotor 11 includes an axially movable piston, and is provided with a friction member 16 on the front cover 2-side lateral surface thereof. When the friction member 16 is pressed onto the front cover 2, the torque is transmitted from the front cover 2 to the input-side rotor 11.

The output-side rotor 12 is disposed in axial opposition to the input-side rotor 11 and is rotatable relatively to the input-side rotor 11. The output-side rotor 12 is coupled to the output hub 5.

The damper 13 is disposed between the input-side rotor 11 and the output-side rotor 12. The damper 13 includes a plurality of torsion springs and elastically couples the input-side rotor 11 and the output-side rotor 12 in a rotational direction. The damper 13 transmits the torque from the input-side rotor 11 to the output-side rotor 12, and also, absorbs and attenuates torque fluctuations.

[Torque Fluctuation Inhibiting Device 14]

FIG. 2A is a front view of the output-side rotor 12 and the torque fluctuation inhibiting device 14. As shown in FIG. 2A, the torque fluctuation inhibiting device 14 includes an inertia ring 20, four centrifugal elements 21, four cam mechanisms 22 and four coil springs 23. The four centrifugal elements 21, the four cam mechanisms 22 and the four coil springs 23 are disposed circumferentially at equal angular intervals of 90 degrees, respectively. It should be noted that as described below, each of the cam mechanisms 22 is composed of a cam follower 25 and a cam 26. Thus, four cam followers 25 are provided, but by contrast, totally eight cams 26 are provided in eight positions located at equal angular intervals.

It should be noted that alternatively, the coil springs 23, disposed on the inner peripheral side of the centrifugal elements 21, respectively, can be omitted as shown in FIG. 2B. Likewise, the coil springs 23 can be provided or omitted in respective examples to be hereinafter explained.

The inertia ring 20 is a continuous annular plate with a predetermined thickness, and is disposed on the outer peripheral side of the output-side rotor 12 such that a predetermined gap is produced radially between the inertia ring 20 and the output-side rotor 12. In other words, the inertia ring 20 is disposed axially in the same position as the output-side rotor 12. Additionally, the inertia ring 20 has a rotational axis, which is the same as that of the output-side rotor 12. The inertia ring 20 is rotatable with the output-side rotor 12, and is also rotatable relatively thereto.

The centrifugal elements 21 are disposed in the output-side rotor 12, and are movable radially outside by centrifugal forces to be generated by rotation of the output-side rotor 12. More detailedly, as shown close-up in FIG. 3, the output-side rotor 12 includes recesses 12 a on the outer peripheral surface thereof. Each recess 12 a is recessed in a rectangular shape from the outer peripheral surface of the output-side rotor 12 toward a rotational center located on the inner peripheral side. Additionally, the centrifugal elements 21 are inserted into the recesses 12 a, respectively, and are radially movable therein. The centrifugal elements 21 and the recesses 12 a are constructed such that a friction coefficient between the lateral surfaces of each centrifugal element 21 and each recess 12 a is set to be less than or equal to 0.1. Moreover, each centrifugal element 21 is a plate having approximately the same thickness as the output-side rotor 12, and includes an outer peripheral surface 21 a having a circular-arc shape. Additionally, each centrifugal element 21 includes a roller accommodation part 21 b recessed inside from the outer peripheral surface 21 a.

As shown in FIG. 3, each cam mechanism 22 is composed of a roller 25 as a cam follower and a cam 26 provided on the inner peripheral surface of the inertia ring 20. The roller 25 is attached to the roller accommodation part 21 b of each centrifugal element 21, and is radially movable together with each centrifugal element 21. It should be noted that the roller 25 can be rotatable in or fixed to the roller accommodation part 21 b. The cam 26 is a circular-arc surface with which the roller 25 makes contact. The roller 25 is moved along the cam 26 when the output-side rotor 12 and the inertia ring 20 are rotated relatively to each other in a predetermined angular range.

Although described below in detail, when rotational phase difference is produced between the output-side rotor 12 and the inertia ring 20 by torque fluctuations, a centrifugal force generated in each centrifugal element 21 and each roller 25 is converted into a circumferential force, by which the rotational phase difference is reduced, due to the contact between each roller 25 and each cam 26. Additionally, when the torque fluctuations are indicated to be a fluctuation value that is, for instance, greater than a predetermined value, the inertia ring 20 is freely rotated with respect to the output-side rotor 12 in the direction that the rotational phase difference is produced.

Each coil spring 23 is disposed between the bottom surface of each recess 12 a and the inner peripheral side surface of each centrifugal element 21, and urges each centrifugal element 21 to the outer peripheral side. Each centrifugal element 21 and each roller 25 are pressed onto each cam 26 of the inertia ring 20 by the urging force of each coil spring 23. Therefore, each roller 25 makes contact with each cam 26 even when a centrifugal force does not act on each centrifugal element 21 in a condition that the output-side rotor 12 is not being rotated.

[Actuation of Cam Mechanisms 22]

Actuation of each cam mechanism 22 (inhibition of torque fluctuations) will be explained with FIGS. 3 and 4. In the lock-up on state, a torque transmitted to the front cover 2 is transmitted to the output-side rotor 12 through the input-side rotor 11 and the damper 13.

When torque fluctuations do not exist in transmitting a torque, the output-side rotor 12 and the inertia ring 20 are rotated in the condition shown in FIG. 3. In other words, the roller 25 in each cam mechanism 22 is contacted to the deepest position (the circumferential middle position) of the cam 26, and the rotational phase difference between the output-side rotor 12 and the inertia ring 20 is “0”.

As described above, the rotation-directional relative displacement between the output-side rotor 12 and the inertia ring 20 is referred to as “rotational phase difference”. In FIGS. 3 and 4, this indicates displacement between the circumferential middle position of each centrifugal element 21 and each roller 25 and that of each cam 26.

On the other hand, when torque fluctuations occur in transmitting a torque, rotational phase difference ±θ is produced between the output-side rotor 12 and the inertia ring 20 as shown in diagrams (a) and (b) of FIG. 4. FIG. 4(a) shows a condition that rotational phase difference +θ is produced to a +R side, whereas FIG. 4(b) shows a condition that rotational phase difference −θ is produced to a −R side.

As shown in FIG. 4(a), when the rotational phase difference +θ is produced between the output-side rotor 12 and the inertia ring 20, the roller 25 of each cam mechanism 22 is relatively moved along the cam 26 to the left side in FIG. 4. At this time, a centrifugal force acts on the centrifugal element 21 and the roller 25. Hence, a reaction force to be received by the roller 25 from the cam 26 has a direction and a magnitude indicated by P0 in FIG. 4(a). A first force component P1 and a second force component P2 are produced by the reaction force P0. The first force component P1 is directed in the circumferential direction, whereas the second force component P2 is directed to move the centrifugal element 21 and the roller 25 toward the rotational center.

Additionally, the first force component P1 acts as a force to move the output-side rotor 12 to the rightward in FIG. 4(a) through each cam mechanism 22. In other words, a force directed to reduce the rotational phase difference between the output-side rotor 12 and the inertia ring 20 is supposed to act on the output-side rotor 12. On the other hand, the second force component P2 moves the centrifugal element 21 and the roller 25 to the radially inner peripheral side against the urging force of the coil spring 23.

FIG. 4(b) shows a condition that the rotational phase difference −θ is produced between the output-side rotor 12 and the inertia ring 20. FIG. 4(b) is similar to FIG. 4(a) regarding the actuation of each cam mechanism 22, although FIG. 4(b) is different from FIG. 4(a) only regarding the moving direction of the roller 25 of each cam mechanism 22 and the directions of the reaction force P0, the first force component P1 and the second force component P2.

As described above, when rotational phase difference is produced between the output-side rotor 12 and the inertia ring 20 by torque fluctuations, the output-side rotor 12 receives a force (first force component P1) directed to reduce the rotational phase difference between the both by the centrifugal force acting on each centrifugal element 21 and the working of each cam mechanism 22. Torque fluctuations are inhibited by this force.

The aforementioned force to inhibit torque fluctuations varies in accordance with the centrifugal force, in other words, the rotational speed of the output-side rotor 12, and also varies in accordance with the rotational phase difference and the shape of each cam 26. Therefore, by suitably setting the shape of each cam 26, characteristics of the torque fluctuation inhibiting device 14 can be made optimal in accordance with the specification of the engine and so forth.

For example, each cam 26 can be made in a shape that makes the first force component P1 linearly vary in accordance with the rotational phase difference in a condition where the centrifugal force acting is constant. Alternatively, each cam 26 can be made in a shape that makes the first force component P1 non-linearly vary in accordance with the rotational phase difference.

When the torque fluctuations further increase and are indicated to be greater than a predetermined fluctuation value, some of the cams 26 on the inertia ring 20 pass the rollers 25, respectively, as shown in FIG. 5. In other words, when excessive torque fluctuations, which are indicated to be for instance greater than the predetermined fluctuation value, are inputted to the output-side rotor 12, the cam mechanisms 22 cause the inertia ring 20 to be freely rotated with respect to the output-side rotor 12 in the direction that the relative displacement is produced. FIG. 5 shows a condition that the inertia ring 20 is being rotated in a −R direction and some of the cams 26, actuated as the cam mechanisms, are moved away from the rollers 25, respectively.

It should be noted that thereafter, each roller 25 is fitted to the next cam 26 (the cam 26 provided on the clockwise side of each roller 25 in FIG. 5). Moreover, when torque fluctuations at this time are indicated to be less than or equal to the predetermined fluctuation value, the cam mechanisms 22 are normally actuated as explained with reference to FIG. 4. Accordingly, torque fluctuations are inhibited. By contrast, when the torque fluctuations are indicated to be greater than the predetermined fluctuation value, the inertia ring 20 is, similarly to the above, configured to be further rotated in the −R direction.

As described above, when excessive torque fluctuations are inputted, some of the cams 26 on the inertia ring 20 are moved across the rollers 25, respectively, and the inertia ring 20 is freely rotated with respect to the output-side rotor 12 in the direction that the relative displacement is produced. Therefore, an excessive force does not act on each cam mechanism 22, whereby breakage or damage of each cam mechanism 22 can be avoided. Additionally, each cam mechanism 22 is not required to be designed to be durable against excessive torque fluctuations, whereby the manufacturing cost of each cam mechanism 22 can be lowered.

[Exemplary Characteristics]

FIG. 6 is a diagram showing exemplary torque fluctuation inhibiting characteristics. The horizontal axis indicates rotational speed, whereas the vertical axis indicates torque fluctuations (rotation velocity fluctuations). Characteristic Q1 indicates a condition without installation of a device for inhibiting torque fluctuations; characteristic Q2 indicates a condition with installation of a well-known dynamic damper device; and characteristic Q3 indicates a condition with installation of the torque fluctuation inhibiting device 14 of the present exemplary embodiment.

As is obvious from FIG. 6, in an apparatus in which the well-known dynamic damper device is installed (characteristic Q2), torque fluctuations can be inhibited only in a specific rotational speed range. By contrast, in the present exemplary embodiment (characteristic Q3), torque fluctuations can be inhibited through the entire rotational speed ranges.

[Modifications of Cam Mechanisms 22]

(Modification 1)

In an exemplary embodiment shown in FIG. 7, at least one friction reducing member 30, taking the form of a bearing, a roller, a resin race, a sheet or so forth, is disposed between each centrifugal element 21 and the lateral surfaces (circumferential end surfaces) of each recess 12 a. When moved, each centrifugal element 21 can be moved as smoothly as possibly by disposing the friction reducing member 30 configured as described above.

(Modification 2)

In an exemplary embodiment shown in FIG. 8, the shape of each centrifugal element and that of the inertia ring are different from those in the aforementioned exemplary embodiment. In other words, an outer peripheral surface 31 a of each centrifugal element 31 is made in the shape of a circular arc recessed to the inner peripheral side. This outer peripheral surface 31 a functions as a cam. On the other hand, an inertia ring 40 includes roller accommodation parts 40 a on the inner peripheral surface thereof. Each roller accommodation part 40 a accommodates each roller 25 functioning as a cam follower. Additionally, each roller 25 makes contact with each outer peripheral surface 31 a functioning as a cam.

This exemplary embodiment is different from the aforementioned exemplary embodiment regarding that each roller 25, functioning as a cam follower of each cam mechanism 32, is disposed on the inertia ring 40 whereas the cam 31 a is provided on each centrifugal element 31, although this exemplary embodiment is similar to the aforementioned exemplary embodiment regarding the other configurations and actuation.

(Modification 3)

FIG. 9 shows an example that the cam follower of each cam mechanism is integrated with each centrifugal element. In other words, each centrifugal element 41 includes a protrusion 41 a on the outer peripheral surface thereof. The protrusion 41 a has a semicircular shape and protrudes to the outer peripheral side. The protrusion 41 a functions as a cam follower and makes contact with each cam 26 provided on the inertia ring 20, whereby a similar actuation to the aforementioned exemplary embodiment is made.

(Modification 4)

FIG. 10 is an example that centrifugal elements are disposed on the inertia ring side whereas the cam mechanisms are disposed on the inner peripheral surface of the output-side rotor. An inertia ring 50 includes recesses 50 a having a rectangular shape on the inner peripheral surface thereof, and centrifugal elements 51 are disposed in the recesses 50 a, respectively, so as to be movable in the radial direction. Additionally, a tension spring 53, pulling each centrifugal element 51 to the outer peripheral side, is provided between each centrifugal element 51 and the bottom surface of each recess 50 a.

On the other hand, each cam mechanism 52 is composed of a roller 55 and a cam 56. The roller 55 is provided as a cam follower on the tip (inner peripheral end) of each centrifugal element 51, whereas the cam 56 is provided on the inner peripheral surface of an output-side rotor 57. The shape of the cam 56 is similar to that of the cam in the aforementioned exemplary embodiment. The roller 55 is constantly contacted to the cam 56 by the urging force of the tension spring 53.

In this exemplary embodiment, when the inertia ring 50 is rotated together with the output-side rotor 57, a centrifugal force directed to the outer peripheral side is generated in each centrifugal element 51. The roller 55 is pressed onto the cam 56 by the centrifugal force. Additionally in occurrence of torque fluctuations, a similar action to the aforementioned exemplary embodiment is made.

Other Exemplary Embodiments

The present disclosure is not limited to the exemplary embodiment described above, and a variety of changes or modifications can be made without departing from the scope of the present disclosure.

(a) The positional relation between the output-side rotor and the inertia ring is not limited to the aforementioned exemplary embodiment. For example, as shown in FIG. 11, contrarily to the aforementioned exemplary embodiment, an output-side rotor 60 can be disposed on the outer peripheral side, whereas an inertia ring 61 can be disposed on the inner peripheral side. The other configurations including the cam mechanisms 22 and so forth are similar to those in the aforementioned exemplary embodiment.

(b) As shown in FIG. 12, an inertia ring, composing the torque fluctuation inhibiting device 14, can be configured to be coupled to the turbine 8. In this case, the turbine 8 is not coupled to the output hub 5. The inertia ring is herein coupled to the turbine 8 (exactly speaking, a turbine shell 8 a), and hence, the turbine shell 8 a also functions as an inertia element (an inertia body) together with the inertia ring.

It should be noted that in an exemplary embodiment shown in FIG. 12, when the lock-up off state is made, a torque from the torque converter body 3 is transmitted from the torque fluctuation inhibiting device 14 to the output-side rotor 12 through the turbine 8, and is then outputted to the output hub 5. At this time, it is difficult to transmit a torque (not torque fluctuations but steady average torque) from the inertia ring to the output-side rotor 12 through the cam mechanisms. Therefore, it is required to reliably produce an angular range in which each of the cam mechanisms is actuated, and besides, it is required to produce a configuration to transmit a torque with springs, mechanical stoppers or so forth.

(c) In the aforementioned exemplary embodiment, each cam mechanism is configured to be actuated when torque fluctuations are indicated to be less than or equal to the predetermined fluctuation value. However, it is also possible to design the specification of each cam mechanism such that as with the case without torque fluctuations, each cam mechanism is configured not to be actuated when torque fluctuations are indicated to be a quite small fluctuation value.

Application Examples

The torque fluctuation inhibiting device described above can be disposed in a variety of settings when applied to a torque converter or other types of power transmission device. Specific application examples will be hereinafter explained with use of schematic diagrams of the torque converter and the other types of power transmission device.

(a) FIG. 13 is a diagram schematically showing a torque converter. The torque converter includes an input-side rotor 71, an output-side rotor 72 and a damper 73 disposed between both rotors 71 and 72. The input-side rotor 71 includes members such as a front cover, a drive plate and a piston. The output-side rotor 72 includes a driven plate and a turbine hub. The damper 73 includes a plurality of torsion springs.

In the example shown in FIG. 13, a centrifugal element is provided on any of the members composing the input-side rotor 71, and a cam mechanism 74 is provided to be actuated with use of a centrifugal force acting on the centrifugal element. A configuration applicable to the cam mechanism 74 is similar to that in the aforementioned respective exemplary embodiments.

(2) In a torque converter shown in FIG. 14, a centrifugal element is provided on any of the members composing the output-side rotor 72, and the cam mechanism 74 is provided to be actuated with use of a centrifugal force acting on the centrifugal element. A configuration applicable to the cam mechanism 74 is similar to that in the aforementioned respective exemplary embodiments.

(3) A torque converter shown in FIG. 15 includes another damper 75 and an intermediate member 76 provided between the two dampers 73 and 75 in addition to the configurations shown in FIGS. 13 and 14. The intermediate member 76 is rotatable relatively to the input-side rotor 71 and the output-side rotor 72, and makes the two dampers 73 and 75 act in series.

In the example shown in FIG. 15, a centrifugal element is provided on the intermediate member 76, and the cam mechanism 74 is provided to be actuated with use of a centrifugal force acting on the centrifugal element. A configuration applicable to the cam mechanism 74 is similar to that in the aforementioned respective exemplary embodiments.

(4) A torque converter shown in FIG. 16 includes a float member 77. The float member 77 is a member for supporting at least one torsion spring composing the damper 73. For example, the float member 77 has an annular shape and is disposed to cover the at least one torsion spring from the outer peripheral side and at least one lateral side. Additionally, the float member 77 is rotatable relatively to the input-side rotor 71 and the output-side rotor 72, and is rotated together with the damper 73 by friction with the at least one torsion spring of the damper 73. In other words, the float member 77 is also rotated.

In the example shown in FIG. 16, a centrifugal element 78 is provided on the float member 77, and the cam mechanism 74 is provided to be actuated with use of a centrifugal force acting on the centrifugal element 78. A configuration applicable to the cam mechanism 74 is similar to that in the aforementioned respective exemplary embodiments.

(5) FIG. 17 is a schematic diagram of a power transmission device that includes a flywheel 80, composed of two inertia bodies 81 and 82, and a clutch device 84. In other words, the flywheel 80, disposed between the engine and the clutch device 84, includes the first inertia body 81, the second inertia body 82 and a damper 83. The second inertia body 82 is disposed to be rotatable relatively to the first inertia body 81. The damper 83 is disposed between the two inertia bodies 81 and 82. It should be noted that the second inertia body 82 includes a clutch cover composing the clutch device 84 as one of the constituent members thereof.

In the example shown in FIG. 17, a centrifugal element is provided on any of the rotary members composing the second inertia body 82, and a cam mechanism 85 is provided to be actuated with use of a centrifugal force acting on the centrifugal element. A configuration applicable to the cam mechanism 85 is similar to that in the aforementioned respective exemplary embodiments.

(6) FIG. 18 shows an example of a power transmission device similar to that in FIG. 17. In this example, a centrifugal element is provided on the first inertia body 81. Additionally, the cam mechanism 85 is provided to be actuated with use of a centrifugal force acting on the centrifugal element. A configuration applicable to the cam mechanism 85 is similar to that in the aforementioned respective exemplary embodiments.

(7) A power transmission device shown in FIG. 19 includes another damper 86 and an intermediate member 87 provided between the two dampers 83 and 86 in addition to the configurations shown in FIGS. 17 and 18. The intermediate member 87 is rotatable relatively to the first inertia body 81 and the second inertia body 82.

In the example shown in FIG. 19, a centrifugal element 88 is provided on the intermediate member 87, and the cam mechanism 85 is provided to be actuated with use of a centrifugal force acting on the centrifugal element 88. A configuration applicable to the cam mechanism 85 is similar to that in the aforementioned respective exemplary embodiments.

(8) FIG. 20 is a schematic diagram of a power transmission device that a clutch device is provided on one flywheel. In FIG. 20, a first inertia body 91 includes one flywheel and a clutch cover of a clutch device 92. In this example, a centrifugal element is provided on any of the rotary members composing the first inertia body 91, and a cam mechanism 94 is provided to be actuated with use of a centrifugal force acting on the centrifugal element. A configuration applicable to the cam mechanism 94 is similar to that in the aforementioned respective exemplary embodiments.

(9) FIG. 21 shows an example of a power transmission device similar to that in FIG. 20. In this example, a centrifugal element 95 is provided on an output side of the clutch device 92. Additionally, the cam mechanism 94 is provided to be actuated with use of a centrifugal force acting on the centrifugal element 95. A configuration applicable to the cam mechanism 94 is similar to that in the aforementioned respective exemplary embodiments.

(10) The torque fluctuation inhibiting device according to the present disclosure can be disposed on any of the rotary members composing the transmission, and furthermore, can be disposed on an output-side shaft (a propeller shaft or a drive shaft) of the transmission, although these configurations are not shown in the drawings.

(11) As another application example, the torque fluctuation inhibiting device of the present disclosure can be further applied to a heretofore well-known dynamic damper device or a power transmission device provided with a pendulum-type damper device.

INDUSTRIAL APPLICABILITY

According to the present disclosure, in a device for inhibiting torque fluctuations in a rotary member, a space can be reduced especially in an axial direction, and besides, a peak of torque fluctuations can be reduced in a relatively wide rotational speed range.

REFERENCE SIGNS LIST

-   1 Torque converter -   12, 57, 60 Output-side rotor -   14 Torque fluctuation inhibiting device -   20, 40, 50, 61 Inertia ring (mass body) -   21, 31, 41, 51, 78, 88, 95 Centrifugal element -   22, 32, 52, 74, 85, 94 Cam mechanism -   23 Coil spring (urging member) -   25 Roller -   26, 31 a, 56 Cam -   30 Friction reducing member -   65 Inertia body -   71 Input-side rotor -   72 Output-side rotor -   73, 75, 83, 86 Damper -   76, 87 Intermediate member -   77 Float member -   80 Flywheel -   81, 91 First inertia body -   82 Second inertia body -   84, 92 Clutch device 

1. A torque fluctuation inhibiting device for inhibiting torque fluctuations in a rotor to which a torque is inputted, the torque fluctuation inhibiting device comprising: a mass body disposed to be rotatable with the rotor and be rotatable relatively to the rotor; a centrifugal element disposed to receive a centrifugal force to be generated by rotation of the rotor and the mass body; and a cam mechanism for making the mass body freely rotate with respect to the rotor when the torque fluctuations inputted to the rotor have a predetermined magnitude or greater, the cam mechanism for converting the centrifugal force that acts on the centrifugal element into a circumferential force when a relative displacement is produced between the rotor and the mass body in a rotational direction, the circumferential force directed to reduce the relative displacement.
 2. The torque fluctuation inhibiting device according to claim 1, wherein the cam mechanism converts the centrifugal force into the circumferential force directed to reduce the relative displacement when the torque fluctuations are indicated to be less than or equal to a predetermined fluctuation value, and makes the mass body freely rotate with respect to the rotor when the torque fluctuations are indicated to be greater than the predetermined fluctuation value.
 3. The torque fluctuation inhibiting device according to claim 2, wherein the cam mechanism makes the rotor and the mass body rotate in synchronization with each other when the torque fluctuations are indicated to be less than the predetermined fluctuation value.
 4. The torque fluctuation inhibiting device according to claim 1, wherein the mass body is disposed on an outer or inner periphery of the rotor.
 5. The torque fluctuation inhibiting device according to claim 4, wherein one of the rotor and the mass body includes a recess on an outer peripheral surface thereof, the one of the rotor and the mass body disposed on an inner peripheral side, and the centrifugal element is accommodated in the recess so as to be movable in a radial direction.
 6. The torque fluctuation inhibiting device according to claim 5, wherein a friction coefficient between the centrifugal element and the recess of the one of the rotor and the mass body is less than or equal to 0.1.
 7. The torque fluctuation inhibiting device according to claim 5, wherein a friction reducing member is disposed between a lateral surface of the centrifugal element and the recess of the one of the rotor and the mass body so as to reduce friction that occurs in movement of the centrifugal element, the lateral surface disposed along a moving direction of the centrifugal element.
 8. The torque fluctuation inhibiting device according to claim 5, wherein the cam mechanism includes a cam follower provided on the centrifugal element, and a cam with which the cam follower makes contact, the cam provided on an inner peripheral surface of the other of the rotor and the mass body, the other of the rotor and the mass body disposed on an outer peripheral side, the cam having a shape for making the circumferential force vary in accordance with an amount of the relative displacement between the rotor and the mass body in the rotational direction.
 9. The torque fluctuation inhibiting device according to claim 8, further comprising: an urging member disposed inside the recess, the urging member for urging the centrifugal element outward in the radial direction such that the cam follower makes contact with the cam while the rotor and the mass body are not being rotated.
 10. The torque fluctuation inhibiting device according to claim 8, wherein the cam follower is a roller disposed on an outer peripheral surface of the centrifugal element.
 11. The torque fluctuation inhibiting device according to claim 8, wherein the cam follower is a protruding part integrated with the centrifugal element, the protruding part provided on an outer peripheral surface of the centrifugal element.
 12. The torque fluctuation inhibiting device according to claim 5, wherein the cam mechanism includes a cam follower provided on an inner peripheral surface of the other of the rotor and the mass body, the other of the rotor and the mass body disposed on an outer peripheral side, and a cam for making contact at an outer peripheral surface thereof with the cam follower, the cam provided on the centrifugal element, the cam having a shape for making the circumferential force vary in accordance with an amount of the relative displacement between the rotor and the mass body in the rotational direction.
 13. The torque fluctuation inhibiting device according to claim 4, wherein one of the rotor and the mass body includes a recess on an inner peripheral surface thereof, the one of the rotor and the mass body disposed on an outer peripheral side, the centrifugal element is accommodated in the recess so as to be movable in a radial direction, and the cam mechanism includes a cam follower provided on the centrifugal element, and a cam with which the cam follower makes contact, the cam provided on an inner peripheral surface of the other of the rotor and the mass body, the other of the rotor and the mass body disposed on an inner peripheral side, the cam having a shape for making the circumferential force vary in accordance with an amount of the relative displacement between the rotor and the mass body in the rotational direction.
 14. A torque converter disposed between an engine and a transmission, the torque converter comprising: an input-side rotor to which the torque is inputted from the engine; an output-side rotor for outputting the torque to the transmission; a damper disposed between the input-side rotor and the output-side rotor; and the torque fluctuation inhibiting device recited in claim
 1. 15. The torque converter according to claim 14, wherein the torque fluctuation inhibiting device is disposed on the input-side rotor.
 16. The torque converter according to claim 14, wherein the torque fluctuation inhibiting device is disposed on the output-side rotor.
 17. The torque converter according to claim 14, wherein the damper includes a first damper to which the torque is inputted from the input-side rotor, a second damper for outputting the torque to the output-side rotor, and an intermediate member provided between the first damper and the second damper, and the torque fluctuation inhibiting device is disposed on the intermediate member.
 18. The torque converter according to claim 14, wherein the damper includes a plurality of coil springs, the torque converter further comprises a float member, the float member rotatable relatively to the input-side rotor and the output-side rotor, the float member for supporting the plurality of coil springs, and the torque fluctuation inhibiting device is disposed on the float member.
 19. A power transmission device comprising: a flywheel including a first inertia body, a second inertia body and a damper, the first inertia body rotated about a rotational axis, the second inertia body rotated about the rotational axis, the second inertia body rotatable relatively to the first inertia body, the damper disposed between the first inertia body and the second inertia body; a clutch device provided on the second inertia body of the flywheel; and the torque fluctuation inhibiting device recited in claim
 1. 20. The power transmission device according to claim 19, wherein the torque fluctuation inhibiting device is disposed on the second inertia body.
 21. The power transmission device according to claim 19, wherein the torque fluctuation inhibiting device is disposed on the first inertia body.
 22. The power transmission device according to claim 19, wherein the damper includes a first damper to which the torque is inputted from the first inertia body, a second damper for outputting the torque to the second inertia body, and an intermediate member provided between the first damper and the second damper, and the torque fluctuation inhibiting device is disposed on the intermediate member. 